Lifting fork for sheet material



Sept. 27, 1966 c. w. BOPP 3,275,367

LIFTING FORK FOR SHEET MATERIAL Filed March 25, 1964 4 Sheets-Sheet l INVENTOR (EM b5301 Sept. 27, 1966 c. w. BOPP LIFTING FORK FOR SHEET MATERIAL Filed March 25 1964 4 Sheets-Sheet 2 IN VENTOR. 656/ M 50/ 1 BY wa Sept. 27, 1966 c. w. BOPP 3,275,367

LIFTING FORK FOR SHEET MATERIAL Filed March 25, 1964 4 Sheets-Sheet 5 INVENTOR. (*Efl In 502 Sept. 27, 1966 c. w. BOF'P LIFTING FORK FOR SHEET MATERIAL 4 SheetsSheet 4 Filed March 25 1964 INVENTOR ('EZIL 1% BOPP JZZZV,

United States Patent Iowa Filed Mar. 25, 1964, Ser. No. 354,613 12 Claims. (Cl. 294-67) The lifting and placing of plasterboard and plywood sheet material is a difficult task inasmuch as these sheets are large and cumbersome to handle. Lifting devices are available which can pick up a plurality of such sheets, but these units cannot negotiate the sheets through openings of limited size, and can usually carry these sheets in only one or possibly two positions. Thus, the placement of sheets in railroad cars and buildings under construction has not heretofore been a substantially mechanical operation.

Therefore a principal object of this invention is to provide a lifting fork for sheet material that can lift a plurality of plasterboard sheets or the like at any desired angle of repose so that the sheets can be easily lifted through an access opening of limited dimensions.

A further object of this invention is to provide a lifting fork for sheet material that can have its angle of repose easily changed from one position to another.

A still further object of this invention is to provide a lifting fork for sheet material that will not damage the sheets as they are being lifted.

A still further object of this invention is to provide a lifting fork for sheet material that is safe to use and operate.

A still further object of this invention is to provide a lifting fork for sheet material that will serve to be self balancing under both loaded and unloaded conditions.

A still further object of this invention is to provide a lifting fork for sheet material that can be used to tilt a plurality of horizontally disposed sheets to a vertical or angular position before they are lifted in such a position to be inserted through an opening that requires such movement of the sheets before they can be inserted therethrough.

A still further object of this invention is to provide a lifting fork for sheet material which is economical of manufacture, durable in use and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings, in which:

FIGURE 1 is a side elevational view of the device of this invention with the dotted lines depicting an alternate position of the support assembly;

FIGURE 2 is a plan view of the device of FIGURE 1 but with the support assembly in an alternate position. The dotted lines of this figure depict the slide frame of the support assembly in an alternate operating position;

FIGURE 3 is a perspective view of the support assembly shown at an enlarged scale;

FIGURE 4 is a plan view of the support assembly shown at a reduced scale with respect to that of FIGURE FIGURE 5 is a side elevational view of the support assembly;

FIGURE 6 is a front elevational view of the lock assembly on the support assembly with portions thereof cut away to more fully illustrate its construction;

be secured to a conventional lifting appartus.

3,275,367 Patented Sept. 27, 1966 "ice FIGURE 7 is a perspective view of the device of this invention in one of its operating positions whereby the sheet material is vertically disposed on one edge;

FIGURE 8 is a perspective view of an alternate operating position of the lifting fork wherein the sheet material is held in a horizontal position;

FIGURE 9 is a third perspective view of the lifting fork disposed in an angular position; and

FIGURE 10 is a sectional view through one arm of the lifting fork taken on line 10--10 of FIGURE 9.

The lifting fork is generally designated by the numeral 10 and includes an elongated bar 12 with arms 14 (FIG- URE 9) extending at right angles from the ends thereof. Times 16 are secured to and extend at right angles from the outer ends of arms 14. Bearing elements 18 (FIG- URE 10) extend outwardly from the sides of arms 14 and rollers 20 are rotatably mounted therebetween in any convenient fashion. If desired, the location of the bearing elements 18 can be staggered on opposite sides of each arm 14 to similarly stagger the positions of the rollers on opposite sides of each arm. It should .be noted (FIGURE 10) that the peripherial surface of the rollers 20 extend beyond the bearing surface 22 of arms 14.

As 'best shown in FIGURE 2, two oppositely disposed spaced apart parallel channels 24 are secured by one end to the central portion of bar 12 and extend outward at right angles therefrom in a direction parallel to that of tines 16. Channel braces 26 extenddiagonally from the ends of bar 12 towards the outer ends of channels 24 where they are secured thereto by welding or the like. Rings 28 are welded to the outer center portions of braces 26. As best shown in FIGURES 1 and 2, .a gusset plate 30 is welded to the inner face of each of the channels 24 at their outer free ends, and plates 32 are welded to plates 30 and channels 24 to reinforce the gusset plates. A plurality of apertures 34 .are located in a semi-circular pattern on plate 30 as indicated in FIG- URE 1. It should be noted that the outermost edge 36 of gusset plate 30 is straight and is in substantial alignment with the outer ends of tines 16.

A support assembly 38 includes a rectangular rigid frame 40 having oppositely disposed side channel members 42 and 42A which are welded to end channels 44 and 44A. Hollow guide tubes 46 and 46A are rectangular in cross-section and are welded to the end channels 44 and 44A, with the rearward ends thereof extending through a suitable opening in the rearward end of channel 44A, and the forward ends thereof, registering with suitable rectangular openings in the forward end channel 44. A lock assembly 47 having spring loaded plungers 47A (FIGURE 5) which are adapted to penetrate the interiors of guide tubes 46 and 46A extends between the center portions of the guide tubes. The structure of the lock assembly 47 will be described in more detail hereafter.

A second frame 48 is slidably mounted within frame 40. Frame 48 has two elongated side tubes 50 and 50A which are rectangular in cross-section and which slide within guide tubes 46 and 46A, respectively, of frame 40. The forward ends of tubes 50 and 50A are welded to cross bar 52 which is of similar construction. The rearward ends of tubes 50 and 50A extend forwardly from guide tubes 46 and 46A, respectively, and terminate inwbearing elements 54. These elements 54 pivot-ally support lift swivel 56 which is adapted to Each of the tubes 50 and 50A have a pair of transversely extending apertures 58 and 60 (FIGURE 5) which are adapted to receive pins 47A of locking assembly 47 at different times.

. pairs of holes 64 and 68 respectively.

3 Substantially triangularly-shaped plates 62 and 62A are welded to the rearward ends of side channels 42 and 42A of frame 40. Plates 62 and 62A are vertically positioned on frame 40 and they extend upwardly therefrom as shown in FIGURES. Gusset plates, 69 extend between channel 44 and plates 62 and 62A to reinforce plates 62 and 62A. Three pairs of vertically aligned apertures 64, 66 and 68 are located in a straight line in these plates. Locking assemblies 70 and 70A are disposed between The plates 62 are adapted .to assume superimposed positions adjacent the inner faces of plates'30 as shown in FIGURES 1 and 2, and nut and bolt assemblies 71 extend through apertures 66 in plates 62 and registering apertures in plates 30 ,to pivotally secure together plates 30 and 62, and hence to pivotally. secure the supporting assembly 38 to the lifting appear in tube 72 between retaining rings 74. Pins.78

slidably extend from opposite ends of tube 72 and a transversely extending actuating pin 79 extends from opposite sides of the inner ends of pins 78. The actuating pins 79 extend through the slots 76 in tube 72 and one end thereof extends into one of the oppositely disposed spiral slots 80 in sleeve 82 which is rotatably mounted on tube 72 between rings 74. Spring 84, which is in a state of compression, yieldingly urges pins 78 outwardly. The fiat portions 80A (FIGURES) in slots 80 yielding hold the pins 78 in their innermost or withdrawn positions when actuating pins 79 are within the portions 80A. A

handle 81 on cylinder 82 facilitates the rotation thereof.

The normal operation of the device of this invention is as follows: A lifting unit 82', which may be mounted on truck 84, includes a boom 86 which can be rotated and elevated with respect to its supporting base .88 by conventional means. A lifting carriage 90 is movably supported by cable 92 which can be actuated to lift the carriage, and which can also move lengthwise of the boom 86 by a second carriage 94 movably supported 1 therein. The operator of the lifting unit canoperate it in conventional fasnion by means of a remote control means. The carriage 90 is connected in any convenient manner to the lift swivel 56 of support assembly 38.

To lift a horizontally disposed pile of sheets 96, the support assembly 38 is placed in the positionshown in FIG- URE 2, and this is accomplished by moving the sleeves 82 on locking assemblies 70 and 70A to the position shown in FIGURE 6, whereupon the pins 78 interlock the plates 62 to the plates 30 by penetrating the upper and lowermost apertures 34 (FIGURE 1) of plate 30. While in an empty condition, the frame 48 moves to the extended balanced position shown by the dotted linesin FIGURES 2 and 3. The tines 16 are inserted underneath the sheets 96. Strap 98 is pivotally secured within recess 100 in each of the tines 16 by hook 102 and a conventional roll pin. Strap 98 is then extended about the ends of the sheets 96, and its other end is then connected in any convenient fashion to ring 28 on braces 26. These straps serve tosupport the sheets to prevent extreme bending thereof. The frame 48 slides to the loaded balanced position shown by the solid lines in FIGURES '2 and} which servesto retain the fork 10 in a balanced or horizontal position (FIGURE 8) :as the sheets are being lifted. The sheets can then be delivered into the wide Window opening 104 in this horizontal condition.

' When it is desired to insert sheets 96 through a narrower opening 106 (FIGURE .7), the pins 78 arewithdrawn from the aperture 34A in plates 30 by rotating sleeves 82 of locking assemblies and 70A. The supporting assembly 38 is then rotated aproximately' 270 degrees in a clockwise direction (as: viewed in FIGURE 1) to the downwardly extending vertical position shown by the dotted lines in FIGURE 1. The pins 78 in locking assembly 70 are then permitted to penetrate'apertures 34A in plates; 30. to lock thesupporting assembly in that position. In}

addition, locking assembly 47 is moved to its locking po-. sition wherein pins 46A penetrate apertures 60 in guide tubes 50 and 50A of frame 48 to prevent any sliding of the frame during the lifting operation. The lifting of the fork 10 will cause it to move to the general position shown in FIGURE 7, where the sheets 96 are in a vertical'position to permit them to be passed through the n'arrowopening 106. Other desired angles of repose of fork 10, such as that shown in FIGURE 9, can be achieved by pivoting and locking the support assembly to the fork in various angular positions.

Thus, it is seen that the fork unit of this invention can be successfully used to move a plurality of sheetsthrough openings of limited size by varying the angle of repose of the fork, and hence, the sheets carried thereon.

Some changes maybe made in the constructionand arrangement of my lifting fork for sheet material without departing from the real. spirit and purpose of my invention, and it is my intention to cover by my claims, any

modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim: I a p 1. In a lifting fork apparatus, a fork means including a normally horizontal frame portion, V a supporting assembly pivotallysecured to said frame v portion, said supporting assembly including a balance] 2. The structure of claim 1 wherein said supporting assembly includes a fixed guideframe, saidbala'nce frame being slidably secured to said guide frame, and means on one of said frames. for selectively locking said frames together. p

3. Ina lifting fork apparatus, v a fork means including a pair of spaced apart vertical arms, an elongated tine secured to and extending at right angles from one end of each ofsaid arms,

a frame structure secured to the ,other e'nds of said.

armsjand extending in a directionparallel-to said tines, upstanding plate members secured to the outer end of said frame structure and having a plurality of apertures therein arranged-in an arcuate pattern, I

a support assembly pivotally securedto said frame.

structure,

a connection means on said support assembly for con nection to an overhead lifting means,

and releasable locking means on said support assembly adapted to be selectively moved to locking engagement with different apertures in said plate members to selectively lock said support assembly in various angular positions with respect to said frame means. 4. The structure-of claim 3 wherein said supporting assembly includes a fixed guide frame,- and a balance frame movably, secured to said guide frame,with said connecting means being secured to said balance frame.

5. The structure of claim 3 wherein said supporting assembly includes a fixed guide frame, and a balance frame slidably secured to said guide frame, with said connecting means being secured to said balance frame and means on one of said frames for selectively locking said frames together 6. The structure of claim 3 wherein the outer faces of said upstanding plates are vertically disposed in substantial alignment with the outer ends of said tines.

7. The structure of claim 3 wherein said support assembly includes two upstanding plate members, and said support assembly is pivotally secured to said frame structure by pivotal means interconnecting the plate members on said frame structure and said support assembly, said releasable locking means being secured to the plate members of said support assembly and including retractable pin elements that can be selectively inserted into the apertures in the plate members of said fiame structure.

8. The structure of claim 3 wherein said support assembly includes two upstanding plate members, and said support assembly is pivotally secured to said frame structure by pivotal means interconnecting the plate members on said frame structure and said support assembly, said releasable locking means being secured to the plate members of said support assembly and including two pairs of retractable pin elements that can be selectively inserted into the apertures in the plate members of said frame structure.

9. The structure of claim 3 wherein said support assembly includes two upstanding plate members, .and said support assembly is pivotally secured to said frame structure by pivotal means interconnecting the plate members on said frame structure and said support assembly, said releasable locking means being secured to the plate members of said support assembly and including two pairs of retractable pin elements that can be selectively inserted into the apertures in the plate members of said frame structure; the apertures in the plate members on said frame structure being in a semicircular pattern with the point of pivotal connection between said plate members being on the geometric center of said semicircular pattern, and the releasable locking means being so positioned on the plates of said support assembly that at least one pair of said retractable pin elements will be in position to be aligned for engagement with a pair of said apertures regardless of the angular position of said support assembly with respect to said frame structure.

10. The structure of claim 3 wherein said support assembly includes two upstanding plate members, and said support assembly is pivotally secured to said frame structure by pivotal means interconnecting the plate members on said frame structure. and said support assembly, said releasable locking means being secured to the plate members of said support assembly and including retractable pin elements that can be selectively insented into the apertures in the plate members of said frame structure; said support assembly including a fixed guide frame, and a balance frame movably secured to said guide frame, with said connecting means being secured to said balance frame. 7

11. The structure of claim 3 wherein said support assembly includes two upstanding plate members, and said support assembly is pivotally secured to said frame structure by pivotal means interconnecting the plate members on said frame structure and said support assembly, said releasable locking means being secured to the plate members of said support assembly and including retractable pin elements that can be selectively inserted into the apertures in the plate members of said frame structure; said support assembly including a fixed guide frame, and a balance frame slidably secured to said guide frame, with said connecting means being secured to said balance frame and means on one of said frames for selectively locking said frames together.

12. The structure of claim 3 wherein roller members are rotatably secured to at least one side of said vertical arms.

References Cited by the Examiner UNITED STATES PATENTS 2,247,168 6/ 1941 Fontaine 29463 2,844,404 7/1958 Haugh. 3,069,196 12/1962 Brooks 29463 3,165,344 1/1965 Holder 29467 GERALD M. FORLENZA, Primary Examiner.

G. F. ABRAHAM, Assistant Examiner. 

1. IN A LIFTING FORK APPARATUS, A FORK MEANS INCLUDING A NORMALLY HORIZONTAL FRAME PORTION, A SUPPORTING ASSEMBLY PIVOTALLY SECURED TO SAID FRAME PORTION, SAID SUPPORTING ASSEMBLY INCLUDING A BALANCE FRAME SLIDABLY MOUNTED THEREON, CONNECTING MEANS ON SAID BALANCE FRAME FOR CONNECTING TO AN OVERHEAD LIFTING MEANS, AND RELATIVELY INTERLOCKING MEANS CONNECTING SAID SUPPORTING ASSEMBLY AND SAID FRAME PORTION WHEREBY SAID SUPPORTING ASSEMBLY CAN BE SELECTIVELY DISPOSED IN ONE OF A PLURALITY OF ANGULAR POSITIONS WITH RESPECT TO SAID FRAME PORTION, SAID BALANCE FRAME BEING SLIDABLY MOVABLE TOWARDS AND AWAY FROM THE PIVOTAL CONNECTION BETWEEN SAID SUPPORTING ASSEMBLY AND SAID FRAME PORTION WHEREBY SAID FORK MEANS WILL BE SELFBALANCING UNDER BOTH LOADED AND UNLOADED CONDITIONS. 